The present invention relates to a compound press-forming apparatus and a compound press-forming method, and particularly to the compound press-forming apparatus and the compound press-forming method, in which press working can be further conducted to a side-face portion of a work, to which press working by an upper die and a lower die has been conducted.
A certain press machine, in which a plurality of steps of press working are conducted by one set of dies constituted of an upper die and a lower die, is shown in Japanese Patent Laid-Open Publication 2000-233239. A compound press die shown in this publication is capable of conducting piercing of an inclined part and shearing/bending of an outer peripheral edge of a flange portion in one stroke.
Herein, a work is set in such manner that its bottom is positioned at the upper side and its flange part is positioned at the lower side. The compound press die includes a lower die that supports the inside face of the work, an upper die that is disposed facing the lower die and moves so as to be accessible to and away from the lower die, a pad that is disposed at the upper die and cooperates with the lower die to hold the outside face of the work when accessing the lower die, a pad ring that is disposed at the outer side of the pad and includes a cutter, a punch that is disposed against the inclined part of the work and supported so as to move in the substantially perpendicular direction to the surface of the inclined part of the work, and punch driving means that moves the punch.
Between the upper die and the lower die, the above-described pad, pad ring, punch, punch driving means, and a die supporting the inside face of the work, a cam operating the punch and a die cushion are provided. The punch driving means is placed inside the dies such that the punch can be moved in the perpendicular direction to the face to be worked (inclined part) to punch at the inclined part of the work, which is different from the movement direction of the upper die going up and down. In the event that a portion for piercing is different from the movement direction of the die and so the movement direction of the punch is different from that of the die, the movement direction is changed by placing the punch driving means constituted of a cam mechanism or a fluid-pressure mechanism inside the die. The punch by the punch driving means is placed at the pad that is disposed at the upper die and the pad is disposed to cover the upper face and the side face of the lower die. The pad is attached to the upper die by a pin interconnecting with a slit formed at the outer face thereof.
Further, in general, press-forming step of, for example, a door panel for vehicles, in which a panel is used as a work, is constituted of a drawing step of drawing the panel as the work into a shape with its desired depth and corners, and an excising step of excising unnecessary parts as scraps from the work that has formed by the drawing step. In the case of forming products with a relatively great depth by drawing, such as a door inner panel for vehicles, such drawing step comprises generally the first drawing step (may also be called just a drawing step) in which the work is formed roughly into a shape with a certain depth, the second drawing step (may also be called a forming step) in which the work is formed into a shape with the desired depth by applying further drawing, and a drawing finishing step (may also be called a listing step) in which the worker is formed into a final shape with its corners of the desired radius-magnitudes and the like. Also, the above-described excising step is a step of excising unnecessary parts of the work for the final product, and comprises generally a peripheral-edge cutting step (may also be called a trimming step) of cutting away a peripheral edge part of the work and a step of partially making holes or cutting (may also be called a piercing step or a notching step).
Herein, in the conventional compound press die shown in the above-described publication, the pad is disposed so as to cover the upper face and the side face of the lower die, and the pin and the slit are provided at the upper side and the outer face of the pad, and the pad ring including the cutter is disposed at the outer side of the pad. Accordingly, for some reasons of an interference or the like, just either work's upper face or inclined face which extends continuously from the upper face could be worked by punching of one press machine, and thus there was a problem that the press machine could not conduct press working to the side face of the work.
Accordingly, in the event that just one press machine is used for press working, the press working is limited by a case where its side face of the work is formed in a simple shape by conducting drawing simply or just holes are informed on its inclined face extending continuously from the upper face of the work.
Further, if it is necessary that further press working is conducted to the side face of the work extending vertically, the work needs to be transferred to another press machine comprising its own-designed dies and punches for further side-face press working. Thus, there were further problems that this additional step of press working would be necessary and additional costs for making these dies and this press working would be required.
Further, in the case of forming products with a relatively great depth by drawing, such as a door inner panel for vehicles, there may be a case where products with such desired depth could not formed by one press stroke of a press machine with upper and lower dies. In this case, it may be necessary that, firstly the first drawing is conducted to a sheet of panel by a certain press machine, next the panel is transfer to another press machine, and then subsequent steps of press working (for example, the second drawing step, drawing finishing step, or excising step) are conducted. In this case, however, when side-face press working is conducted to a side-face of the work (door inner panel for vehicles), the work needs to be transferred to the third press machine for the side-face press working as well. Thus, there was also a problem of the necessity of additional steps of press working, thereby complicated steps and cost increases.